Graphical user interface for a portion of a display screen



FIGURE is a front view of a user interface for a portion of a display screen showing our new design.

The three broken line parallelograms and the partial rectangle and the unshaded areas there within form no part of the claimed design. The broken line showing of the display screen and text is included for the purpose of illustrating environment and forms no part of the claimed design. 

The ornamental design for a graphical user interface for a portion of a display screen, as shown and described. 